Intumescent compositions are generally known in the art; when exposed to heat and fire and upon swelling they form a thick, relatively non-flammable insulating carbonaceous skeleton. The essential active components of such compositions include a carbon source which ultimately forms the insulating carbonaceous skeleton, a spumescent which affects the thickness or the swelling of the products formed upon burning and an acid catalyst, such as an acidic phosphoric acid compound, which initiates the intumescence reaction when exposed to heat. In the past, intumescent compositions have been applied as surface paints or other coatings onto substrates to reduce the flammability of the substrate and protect the substrate from damage due to intensified heat and flames.
Conventional intumescent paints and coatings generally comprise dispersions of a carbon source, a spumescent and an acid catalyst in combination with binders, thickeners, solvents, pigments and the like. Such coatings have proven only marginally effective in protecting the underlying substrate from fire damage, however, because the dispersed active intumescent components are relatively far apart, in molecular terms, from one another within the composition. Thus, there is needed some time for the transport and the internal mixing of said essential components which delays the intumescent reaction and prevents the immediate protection of the substrate.
Integrated polymer compositions, wherein all of the components needed for intumescence are provided within the polymer chain, have more recently been developed in the art. These compositions have proven more effective than the intumescent coatings described above, probably because the components necessary for intumescence are closely held together in the polymer chain and thus a short or no transport time at all is required for the initiation of the intumescence process.
As these polymer formulations offer the potential for added protection there is a need to further improve them and to provide methods of producing the same for effective use in a variety of industrial and commercial applications and to enable easy on-site application of the same.
Of particular interest are intumescent coatings which have been proposed and used as protective coatings for structural elements which separate compartments to prevent the passage of fire from one compartment to an adjacent one. Many fire walls or barriers previously used in construction, however, were either not treated with a protective intumescent coating, because such coatings were not known at the time of the construction, or were treated with inferior dispersion-type coatings that have lost effectiveness over time and weathering. Because of the restricted space in which such barriers are generally located, it is often difficult and expensive to replace such structural elements with newly coated barriers.
Thus, there is a need for effective intumescent coating compositions that can be easily applied to permanently affixed barriers, on-site and in a relatively short period of time. In addition, the resulting coating preferably should not release noxious fumes or otherwise require the use of dangerous solvents during application, since the barriers requiring coating are frequently in relatively compact and unventilated areas. A further preferred property of such a coating would be an absence of noxious or toxic fumes created upon undergoing the intumescence process, as such fumes are dangerous to persons in the vicinity of the fire.